Carburetor



W. STURM May 10, 1932.

CARBURETOR Filed Sept. 23, 1929 Patented May 10, 1932 UNITED STATESWILHELM STUBM, OF STUTTGART, GERMANY, ASSIGNOR '10 ROBERT BOSCH Am-PATENT OFFICE GESELLSCEAFT, OF STUTTGABT, GERMANY GABBURETOB Applicationfiled September 23, 1929, Seria'lR'o. 394,662, and in Germany October26, 1928.

The present invention relates to carburetors.

A carburetor has already been proposed in which the total crosssectional area of the carburetor pipe before the fuel nozzle isregulated by a mechanically actuated air throttle and thecross-sectional area of an air passage in an auxiliary air chamberoutside the choke tube by a second throttle adjustable corresponding tothis air throttle. The vacu um for raising the fuel from the main tankinto the float chamber and from the latter into the carburetor housingis set up in choke tubes arranged behind one another in the carburetorhousing. This arrangement has the disadvantage that principal parts ofthe carburetor are diflicult of access and assembly is diflicult.According to this invention a carburetor is considerably simplified byusing a mixture throttle located to the rear of the choke tubes as amechanically actuated main throttle, instead of a main air throttle, andby having the choke tubes for feeding the fuel into the float chamberand sucking it out of the same attached radially and outwardly to themixing pipe or main choke tube in the mixing pipe which is controlled bythe air throttle. The vacuum in the float chamber is thereby maintainedon running light and with the main throttle slightly open by anautomatic regulating device.

Several forms of construction of the invention are shown in section inthe accompanying drawings.

Figure 1 shows a carburetor with one auxiliary choke tube.

Figure 2 showsa carburetor with two auxiliary choke tubes and a lightrunning device.

Figure 3 shows a-regulating arrangement for the fuel pipe.

Figure 4 is a view of Figure 1, partly in section, taken to the left ofa vertical line located between the valve 8' and the float chamber 71,.

Figure 5 is a view of Figure 2, partly in section, taken to the left ofa vertical line located between the valve 5 and the float chamber 72..

An adjustable mixture valve 6 and an air throttle valve 0 whichautomatically adjusts itself according to the speed of the engine or Ving'constriction or jet f in the bore thereof is arranged at the pointwhere the maximum vacuum is obtained in this auxiliary choke tube whilsta connecting duct 9 opens at a point where the vacuum is low. A valve 81is mounted on the air throttle e and automatically adjusts itselfaccording to the mixture throttle b and alters the free cross sectionalarea of the auxiliary choke tube according to. the position of theairthrottle a. When the mixture throttle b is closed or nearly closed thevalve 6 reduces the free cross-sectional area of the auxiliary choketube to a minimum in order to maintain a suflicient vacuum in the floatchamber even when running light. The vacuum at the nozzle of the fuelpipe is thereby also reduced.

In the form of construction shown in Figure 2, a further auxiliary choketube is arranged on the axis of the auxiliary choke tube 6, whichreceives the nozzle of the fuel pipe. The float chamber h is connectedwith the auxiliary choke tube e by the duct g. It may however equallywell open into the choke tube In at a point where a lower vacuum obtainsthan at the fuel nozzle.

A valve Z is built on to the mixture throttle b which keeps the freeaperture of the auxiliary choke tube closed on running light and up to apredetermined opening of the throttle b. The fuel is in thiscase-supplied through a slow running device m; n.

If the speed of the engine drops without the throttle I) being closedwhen the load on the engine is greater, the air throttle or choke valveccloses the mixing pipe correspondingly. The suction air currenttherefore passes principally through the auxiliary choke tube and theresets up suflicient vacuum to suck the fuel into the float chamber. Thisvacuum is however in excess ofthat required to suck the fuel from thefloat chamber and the fuel delivery past the jet f must therefore besuitably regulated. This can be effected in various ways.

In the form of construction shown in Figure 1 the velocity with whichthe air passes through the choke tube 6 varies with the position of thevalve 2' of the automatic throttle or choke valve 0. The amount of fueldelivered past the jet 7 varies accordingly.

The carburetor in Figure 2 regulates the delivery of fuel by venting thefuel pipe. For this purpose the latter is connected by a duct 0 and-achoke tube ;0 with the chamber controlled by the air throttle 0'. Thechoke tube 12 can be omitted in cases where direct entry of air into theduct 0 is suitably reduced when the throttle 0' is fully open. Incontrary cases two auxiliary choke tubes 7) (not shown) may also bearranged one inside the other.

Figure 3 shows a mechanical regulation of the fuel metering orifice f.In this case a needle Q is positively displaced according to theposition of the automatic throttle or choke valve, thereby altering thecross-section of the said orifice.

7 Each of these types of regulation can be used with all the forms ofconstruction of the carburetor.

What I claim is:

1. A carburetor comprising a mixing tube, a mixture throttle valve andan air throttlev valve in said mixing tube, at least one choke tubedirectly extending into the atmosphere radially outwards from the mixingchamber of said mixing tube at a point between said throttle valves,said air throttle valve directly controlling the whole air flow to themixing chamber except the air flow entering through said radiallyextending choke tube, a float chamber, a fuel pipe leading from the fuelspace of the float chamber to a point of high vacuum in a radiallyextending choke tube and a connection from the air space of the floatchamber to a point of lowerbvacuum in a radially extending choke tu e.

2. A carburetor comprising a mixing tube, a manually operated mixturethrottle valve and an automatically operated air throttle valve in saidmixing tube, at least one choke tube extending radially outwards fromsaid mixing tube between said throttle valves and directly proceedingfrom the mixing chamber of said mixing tube into the atmosphere, saidair throttle valve adapted to directly control the whole air flow tosaid mixing chamberexcept the air flow entering through said choke tube,a float chamber, a fuel pipe leading from the fuel space of said floatchamber to a point of high vacuum in a radially extending choke tube anda connection from the air space of the float chamber to a point of lowervacuum in a choke tube radially extending.

3. A carburetor comprising a mixing tube,

a mixture throttle valve and an air throttle valve in said mixing tube,a main choke tube in said mixing tube intermediate of said throttlevalves, an auxiliary choke tube extending radially outward from saidmain choke tube, a second auxiliary choke tube partly within andextending axially outwards from said auxiliary choke tube, a floatchamber, a connection between the air space of the float chamber andsaid auxiliary choke tube and a fuel pipe leading from the fuel space ofthe float chamber to said second auxiliary choke tube.

4. A carburetor comprising a mixing tube, a mixture throttle valve andan air throttle valve in said mixing tube, a main choke tube in saidmixing tube intermediate of said throttle valves, at least one auxiliarychoke tube extending radially outwards from said main choke tube, afloat chamber, a fuel pipe leading from the fuel space of said floatchamber to a point of high vacuum in a second auxiliary choke tubewithin the first auxiliary tube, a connection between the air space ofsaid float chamber and a point of lower vacuum in one of said auxiliarychoke tubes and automatic valve means controlling the freecross-sectional area of the mouth of the radially outermost choke tubeand adapted substantially to close said mouth when the engine is runningat light load.

5.; A carburetor comprising a mixing tube, a mixture throttle valve andan air throttle valve in said mixing tube, a main choke tube in saidmixing tube intermediate of said throttle valves, at least one auxiliarychoke tube extending radially outwards from said main choke tube, afloat chamber, a fuel pipe leading from the fuel space of said floatchamber to a point of high vacuum in a second auxiliary choke tubewithin the first auxiliary tube, a connection between the air space ofsaid float chamber and a point of lower vacuum in one of said auxiliarychoke tubes, and valve means operatively connected with the mixturethrottle valve controlling the free cross-sectional area of the mouth ofthe radially outermost choke tube.

6. A carburetor comprising a mixing tube, a mixture throttle valve andan air throttle valve in said mixing tube, a main choke tube in saidmixing tube intermediate of said throttle yalves, an auxiliary air tubeembodying at least one auxiliary choke tube extending radially outwardsfrom said main choke tube, a float chamber, a fuel pipe leading from thefuel space of said float chamber to a point of high vacuum in anauxiliary choke tube in said air tube, a connection between the airspace of said float chamber and a point of lower vacuum in an auxiliarychoke tube in said air tube, and valve means operatively connected withthe air throttle valve controlling the free cross-sectional area of themouth of the auxiliary air tube.

7 A carburetor comprising a mixing tube,

a mixture throttle valve and an air throttle crbss-sectional area of themouth of the auxiliary air tube, and a slow running fuel duct extendingfrom the float chamber to a point in the mixing tube on the suction sideof the main choke tube.

8. A carburetor comprising a mixing tube,

a mixture throttle valve and an air throttlevalve in said mixing tube, amain choke tube in said mixing tubev intermediate of said throttlevalves, at least one auxiliary choke tube extending radially outwardsfrom said main choke tube, a float chamber, a fueLpip'e leading from thefuel space of said float chamber to a point of high vacuum in anauxiliary choke tube, a connection between the air space of said floatchamber and a point of lower vacuum in a second auxiliary choke tubesurrounding said first auxiliary tube, valve means controlling tionalarea of the mouth of the radially outermost choke tube, and valve meanscontrolling the eflective cross sectional area of the fuel pipe inaccordance with the free crosssectional area of the air passage throughthe mixing tube.

9. A carburetor comprsing a mixing tube, a mixture throttle valve and anair throttle valve in said mixin tube, a main choke tube in said mixingtu e intermediate of said throttle valves, at least one auxiliary choketube extendin radially outwards from said main choke tu a float chamber,a fuel pipe leading from the fuel space of said float chamber to a pointof high'vacuum in an auxiliary choke tube, a connection between the airspace of said float chamber and a point of lower vacuum in a secondauxiliary choke tube, said auxiliary choke tubes being arranged onewithin the other, valve means controlling the free cross sectional areaof the mouth of the radially outermost choke tube.

and valve means operatively connected with the air throttle valve forcontrolling the flow of fuel in the fuel pipe.

10. A carburetor comprising a mixing tube, a mixture throttle valve andan air throttle valve in said mixing tube, a main choke tube in saidmixing tube intermediate of said throttle'valves, at least one auxiliarychoke tube extendin radially outwards from said main choke tube, a floatchamber, a fuel pipe the free cross-sec leading from the fuel space ofsaid float chamber to a point of high vacuum in an auxiliary choke tube,a connection between the air space of said float chamber and a point oflower vacuum in a second auxiliary choke tube, said auxiliary choketubes being arranged one within the other, valve means controlling thefree cross-sectional area of the mouth of the radially outermost choketube, and a regulating air duct extending from the fuel pipe to a pointin the mixing tube in ad vance of the main choke tube. I

11. A carburetor comprising a mixing tube, v

a mixture throttle valve and an air throttle valve in said mixin tube, amain choke tube in said mixing tube intermediate of said throttlevalves, at least one auxiliary choke tube extending radially outwardsfrom said main choke tube, a float chamber, a fuel pipe leading from thefuel space of said float chamber to a point of high vacuum in anauxiliary choke tube, a connection between the air space of said floatchamber and a point of lower vacuum in a second auxiliary choke tube,said auxiliary choke tubes being arranged one within the other, valvemeans controlling the free cross-sectional area of the mouth of theradially outermost choke tube,.an auxiliary choke tube in the mixingpipe located in advance of the main choke tube and an air duct extendingfrom. said auxiliary choke tube to the fuel pipe.

12. A carburetor comprising a mixing tube, a mixture throttle valve andan air throttle valve in said mixin tube, a main choke tube in saidmixing tu intermediate of said throttle valves, at least one auxiliarychoke tube extendin radially outwards from said main choke tu e, a floatchamber, a fuel pipe leading from the fuel space of said float chamberto a point of hlgh vacuum in an auxiliary choke tube, a connectionbetween the air space of said float chamber and a point of lower vacuumin a second auxiliary choke tube, said auxiliary choke tubes beingarranged one within the other, valve means controlling the freecross-sectional area of the mouth of the radially outermost choke tube,

and means for supplying air to the fuel ipe

